According to the documentation, the InputFile constructor already
analyses the header of the given file.

To keep the same API in bindings (if there is no getter, SWIG
automatically generates methods to access the attributes.)

Need to declare Video/AudioStat before ProcessStat, to enable SWIG to
know the type of the objects manipulated by ProcessStat.

* Need to find stream info before get them as properties.
* Need to have FileProperties attribute as pointer, because we want to
create it only once (after _formatContext.findStreamInfo()).

…into dev_addTestsForProcessStat

…into dev_addTestsForProcessStat